As is generally well known, heating of a passenger compartment in a transit vehicle is achieved by a combination of several heating components. One heating component, which is known as a conventional baseboard electric heater, is installed longitudinally and in series on each side of the transit vehicle either at a juncture of the floor and the side wall or directly within the side wall and being somewhat elevated from the floor of the vehicle. Mounting of the baseboard heaters is interrupted by the side doors located within each side wall of the transit vehicle and which are used for passenger ingress and egress. The actual finned electric heating element is positioned behind a grill mesh that enables the generated heat to flow into the seating area. Baseboard heaters generate about forty percent of the required total heating energy. Additionally, the heat generated by baseboard heaters may be routed, by way of convection, within the side walls for entering the passenger compartment through the grills generally positioned slightly below the bottom edge of the side window.
Another heating component is mounted in series on the roof of the transit vehicle with generated heat being forced in a downward fashion via blowers into the passenger compartment from the grills positioned within or near a ceiling of such transit vehicle. Such roof mounted heaters generate remaining sixty percent of the total heating energy.
There are number of disadvantages of using baseboard heaters for heating passenger compartment of the transit vehicle.
Such heaters occupy between about ten and about twelve percent of the vehicle width thus reducing the actual usable space of the passenger compartment.
Use of stainless steel enclosures and fined electrical heating elements increase the installation costs, particularly in vehicles wherein the heating elements are mounted within the side wall and require structural supports which further increase the weight of the vehicle.
Baseboard heating elements typically operate at a temperature between about 400 degrees Fahrenheit and about 500 degrees Fahrenheit. Grills are positioned to maintain surface temperature of less than 125 degrees Fahrenheit as mandated by Americans With Disability Act (ADA). However, such baseboard heaters have been regarded as fire hazards due to the often close proximity of flammable items such as clothing, coats, baby blankets, briefcases, and the like. A heat transfer loss occurs through the portion of the side wall containing such baseboard heaters due to lack of insulation.
Baseboard heaters generally require the use of stainless steel enclosures and grills due to harsh chemicals being used in floor cleaning, which increases the installation costs.
Floor areas disposed adjacent each side door used for passenger ingress and egress are poorly heated, resulting in frequent floor structure failures due to moisture, such as rain, snow and sleet, entering the transit vehicle when doors are opened and as passengers ingress and egress the vehicle. Accordingly, door threshold heaters, when employed, must be designed to heat a portion of the vehicle adjacent to each side door resulting in increased manufacturing costs.
The baseboard heaters do not generally heat a portion of the floor, which is disposed along the longitudinal centerline of the transit vehicle and is further disposed between the seats. Standing passengers which use such portion of the floor are standing on a colder floor surface. It has been proven that a person experiences bodily warmth if ones feet are warmed despite a cool ambient temperature. Accordingly, higher heat energy must be generated from roof mounted heaters to compensate for this condition.
Therefore, there is a need for an improved system for at least partially heating passenger compartment of the transit vehicle.